US20110044120A1 - Semiconductor device - Google Patents
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- US20110044120A1 US20110044120A1 US12/860,058 US86005810A US2011044120A1 US 20110044120 A1 US20110044120 A1 US 20110044120A1 US 86005810 A US86005810 A US 86005810A US 2011044120 A1 US2011044120 A1 US 2011044120A1
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 60
- 230000005540 biological transmission Effects 0.000 claims abstract description 220
- 230000000873 masking effect Effects 0.000 claims abstract description 78
- 230000015654 memory Effects 0.000 claims description 70
- 230000000295 complement effect Effects 0.000 claims description 10
- 230000002093 peripheral effect Effects 0.000 claims description 7
- 230000008859 change Effects 0.000 claims description 5
- 230000004044 response Effects 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 16
- 238000003491 array Methods 0.000 description 13
- 230000004048 modification Effects 0.000 description 6
- 238000012986 modification Methods 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 229910017997 MIO3 Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
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- 230000004913 activation Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
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- 239000011159 matrix material Substances 0.000 description 1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/10—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers
- G11C7/1048—Data bus control circuits, e.g. precharging, presetting, equalising
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/4063—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing
- G11C11/407—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing for memory cells of the field-effect type
- G11C11/409—Read-write [R-W] circuits
- G11C11/4094—Bit-line management or control circuits
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/4063—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing
- G11C11/407—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing for memory cells of the field-effect type
- G11C11/409—Read-write [R-W] circuits
- G11C11/4096—Input/output [I/O] data management or control circuits, e.g. reading or writing circuits, I/O drivers or bit-line switches
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/10—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers
- G11C7/1051—Data output circuits, e.g. read-out amplifiers, data output buffers, data output registers, data output level conversion circuits
- G11C7/1066—Output synchronization
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/10—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers
- G11C7/1078—Data input circuits, e.g. write amplifiers, data input buffers, data input registers, data input level conversion circuits
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/10—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers
- G11C7/1078—Data input circuits, e.g. write amplifiers, data input buffers, data input registers, data input level conversion circuits
- G11C7/1096—Write circuits, e.g. I/O line write drivers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/12—Bit line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, equalising circuits, for bit lines
Definitions
- This invention relates to a semiconductor memory and semiconductor device. More particularly, the invention relates to a semiconductor memory and semiconductor device having a write mode in which data masking is performed and a write mode in which data masking is not performed.
- Patent Document 1 describes a semiconductor storage device in which write data is input to a synchronous DRAM at a speed that is an integral number of times greater than the clock frequency, a data masking signal is input in synch with the input data and data masking can be performed for every bit of the write data.
- JP-H11-45568A which corresponds to U.S. Pat. No. 6,052,330.
- the write amplifier does not operate to send the data to the data transmission line.
- the data transmission line is connected, while still in the pre-charged state, to the sense amplifier selected by the column address.
- the potential on the bit line of the sense amplifier fluctuates owing to charge sharing when the selection switch that connects the data transmission line and the sense amplifier is turned on by the column address.
- the data in the sense amplifier will not be destroyed even if fluctuation of the bit-line potential occurs.
- the sense amplifier will perform signal inversion erroneously if an imbalance in the threshold value becomes too large owing to process variations.
- microfabrication is accompanied by a decline in the supply voltage of the memory cell array, measures for dealing with the write mode in which data masking is performed have become important.
- a semiconductor memory including a data transmission line and a data transmission line precharge circuit.
- the data transmission line precharge circuit sets a precharge potential of a data transmission line to a first potential at the time of a first write mode in which data masking is not performed.
- the data transmission line precharge circuit sets the precharge potential to a potential different from the first potential at the time of a second write mode in which data masking is performed.
- a semiconductor memory including a memory cell array including a plurality of bit lines, a plurality of selection switches each connected to a corresponding one of the plurality of bit lines, a plurality of write amplifiers, and a plurality of data transmission line pairs.
- Each of the transmission line pairs which connects a corresponding one of the write amplifiers and corresponding ones of the plurality of selection switches.
- Each of the plurality of data transmission line pairs transmits output data of the corresponding write amplifier as a pair of complementary signals, which includes a non-inverted signal and an inverted signal, at write time.
- the semiconductor memory further includes a data transmission line precharge circuit precharges the plurality of data transmission line pairs to a first potential and subsequently sets, to an intermediate potential, a precharge potential of a data transmission line pair that performs data masking among the plurality of data transmission line pairs at write time.
- the intermediate potential is a potential that is intermediate the first potential and a second potential at which the write amplifier discharges one data transmission line of a data transmission line pair that does not perform data masking at write time.
- a semiconductor device including write amplifiers of a plurality of bits, data transmission lines of a plurality of bits connected to respective ones of the write amplifiers of the plurality of bits, and a plurality of flip-flops connected to the data transmission lines of each of the bits via respective ones of selection switches.
- the semiconductor device further including a data transmission line precharge circuit that exercises control such that before data of the plurality of bits is written from the write amplifiers to flip-flops selected by the selection switches via the data transmission lines, precharge potential of the data transmission lines is made a first potential with regard to bits that do not perform data masking, and precharge potential of data transmission lines that perform data masking is made a potential different from the first potential.
- data write is executed after a data transmission line is precharged to a potential when data masking is performed and to a different potential when data masking is not performed.
- precharging is performed to a potential at which data can be written in excellent fashion.
- precharging can be performed to a potential that suppresses a fluctuation in bit-line potential.
- FIG. 1 is a block diagram illustrating the entirety of a semiconductor memory according to an exemplary embodiment of the present invention
- FIG. 2 is a block diagram illustrating a bank 0 of semiconductor memory according to the exemplary embodiment
- FIG. 3 is a block diagram illustrating DQ 0 of bank 0 in the semiconductor memory according to the exemplary embodiment
- FIG. 4 is an operation waveform diagram in the case of a write mode in which data masking is performed in the semiconductor memory according to the exemplary embodiment
- FIG. 5 is a circuit diagram of a read/write control circuit in the semiconductor memory according to the exemplary embodiment
- FIG. 6A is a circuit diagram illustrating a modification and FIG. 6B a circuit diagram illustrating another modification of a data transmission line precharge circuit and write amplifier circuit in the semiconductor memory according to the exemplary embodiment;
- FIG. 7 is an operation waveform diagram in the case of a write mode of bits in which data masking is performed and of bits in which data masking is not performed in the semiconductor memory according to an exemplary embodiment.
- FIG. 8 is a circuit diagram illustrating another modification of a data transmission line precharge circuit in the semiconductor memory according to the exemplary embodiment.
- the present invention provides a semiconductor memory having a data transmission line precharge circuit for exercising control such that a precharge potential of a data transmission line is made a first potential at the time of a first write mode in which data masking is not performed, and the precharge potential of the data transmission line is made a potential different from the first potential at the time of a second write mode in which data masking is performed.
- precharging can be performed to a potential suited to high-speed data write.
- precharging can be performed to a potential that suppresses a fluctuation in the potential of a bit line connected to the data transmission line.
- the side of a memory cell array that receives data on a data transmission line need not have its circuit configuration or operation changed depending upon whether or not data masking is carried out. Further, in a case where data of a plurality of bits is written in parallel, whether data masking is to be performed can easily be set on a bit-by-bit basis.
- FIG. 1 is a block diagram illustrating the entirety of a semiconductor memory according to this exemplary embodiment of the present invention.
- a semiconductor memory 100 is a DDR3 SDRAM (Double-Data-Rate 3 Synchronous Dynamic Random-Access Memory) includes eight banks.
- this DDR3 SDRAM is strictly an example of a preferred exemplary embodiment and the scope of application of the present invention is not limited to a DDR3 SDRAM.
- the invention is applicable to a semiconductor memory other than a DRAM and to a semiconductor device other than a semiconductor memory.
- the semiconductor memory 100 is provided with 16 data input/output terminals 103 corresponding to bits DQ 0 to DQ 15 .
- Each data input/output terminal 103 is connected to a read/write control circuit 102 of each bank via an input/output circuit, not shown.
- Memory cell array areas 101 of banks 0 to 7 are arranged by being divided into eight lower-order bits (DQ 0 to DQ 7 ) and eight higher-order bits (DQ 8 to DQ 15 ) (namely into left and right halves as shown in the drawing).
- the read/write control circuit 102 is provided for every memory cell array area 101 of each bank of the eight lower-order bits and eight higher-order bits.
- the data input/output terminals (DQ 0 to DQ 15 ) of the eight lower-order bits are connected to the read/write control circuit 102 corresponding to the memory cell array area in which the eight lower-order bits are disposed, and the data input/output terminals (DQ 8 to DQ 15 ) of the eight higher-order bits are connected to the read/write control circuit 102 corresponding to the memory cell array area in which the eight higher-order bits are disposed.
- An LDM terminal 105 and a UDM terminal 106 are terminals for data-masking write data of the eight lower-order bits (DQ 0 to DQ 7 ) and eight higher-order bits (DQ 8 to DQ 15 ), respectively. Whether masking is performed or not can be changed over for every bit of data, which is input serially from the corresponding data input/output terminals (DQ 0 to DQ 7 , DQ 8 to DQ 15 ), using both edges, namely the rising and falling edges of a data strobe signal (DQS) (not shown), as a reference.
- DQS data strobe signal
- the LDM terminal is connected to the read/write control circuits 102 corresponding to the memory cell array areas 101 (the memory cell array areas 101 on the left side in FIG. 1 ) in which the bits DQ 0 to DQ 7 of each bank are disposed.
- the UDM terminal is connected to the read/write control circuits 102 corresponding to the memory cell array areas 101 (the memory cell array areas 101 on the right side in FIG. 1 ) in which the bits DQ 8 to DQ 15 of each bank are disposed.
- FIG. 2 is a block diagram illustrating bank 0 of semiconductor memory.
- FIG. 2 corresponds to a diagram obtained by extracting the memory cell array areas 101 and read/write control circuits 102 of bank 0 of lower-order bits (DQ 0 to DQ 7 ) and bank 0 of higher-order bits (DQ 8 to DQ 15 ).
- a read/write bus RWBS which includes bus wiring connected to the data input/output terminals (DQ 0 to DQ 7 ), and an LDM signal, which is a DQ 0 to DQ 7 data masking signal connected to the LDM terminal 105 , are connected to the read/write control circuit 102 of the lower-order bits (DQ 0 to DQ 7 ).
- a read/write bus RWBS connected to the data input/output terminals (DQ 8 to DQ 15 ), and a UDM signal, which is a DQ 8 to DQ 15 data masking signal, are connected to the read/write control circuit 102 of the higher-order bits (DQ 8 to DQ 15 ).
- the read/write control circuits 102 are connected to the memory cell array areas 101 of the bits (DQ 0 to DQ 7 , DQ 8 to DQ 15 ) via main data transmission lines (main I/O lines) MIO_T, MIO_B.
- the main data transmission lines MIO_T, MIO_B are bi-directional data transmission lines and are used in data transmission for writing write data and reading read data. These data transmission lines are data transmission lines for transmitting complementary signals comprising a non-inverted signal (True) and an inverted signal (Bar, namely the complement of the True signal).
- the memory cell array area 101 has been divided into individual bits (DQ 0 to DQ 15 ). Disposed in the memory cell array area 101 of every bit, in addition to the memory cell array per se, are local data transmission lines (local I/O lines) LIO_T, LIO_B, selection switches (Y switches) and sense amplifiers, etc.
- the local data transmission lines LIO_T, LIO_B are data transmission lines connecting the main data transmission lines MIO_T, MIO_B and the memory cell array.
- the selection circuits are switches connecting the local data transmission lines LIO_T, LIO_B and the bit lines of the memory cell array.
- the sense amplifiers are connected to the bit lines of the memory cell array and amplify the bit-line potentials read out of the memory cells.
- the read/write control circuit 102 is a circuit for controlling the read/write operation of the memory cell array.
- write data that has been sent in serially via the read/write bus RWBS is converted to parallel data by the read/write control circuit 102 and is written to the memory cell array.
- 8-bit pre-fetch is employed and therefore the write data that has been sent in serially from the read/write bus RWBS is rearranged into 8-bit parallel data and sent to the memory cell array in 8-bit parallel fashion via the data transmission lines.
- FIG. 3 is a block diagram illustrating a portion of DQ 0 of bank 0 in the semiconductor memory 100 .
- FIG. 3 shows only one set of the main data transmission lines MIO_T, MIO_B is shown.
- FIG. 3 includes the read/write control circuit 102 and the circuit of the memory cell array area 101 of the portion relating to DQ 0 of bank 0 in FIG. 2 .
- FIG. 3 includes the read/write control circuit 102 and the circuit of the memory cell array area 101 of the portion relating to DQ 0 of bank 0 in FIG. 2 .
- a main data line precharge circuit (data transmission line precharge circuit) 302 corresponds to the read/write control circuit 102 in FIG. 2 , and the other blocks correspond to the memory cell array area 101 .
- the main data line precharge circuit (data transmission line precharge circuit) 302 precharges the main data transmission lines MIO_T, MIO_B.
- the main data transmission lines MIO_T, MIO_B transmit a pair of complementary signals comprising a non-inverted signal and an inverted signal.
- a precharge signal (inverted signal) PCH-B is connected to the main data line precharge circuit 302 as a signal for controlling precharging.
- a write-amplifier enable signal WAE, a DQ 0 to DQ 7 data mask holding signal LDMH and a data mask precharge signal LDMPRE are connected to the main data line precharge circuit 302 as signals for controlling precharge potential at the time of a second write mode, which is a mode for performing data masking.
- the DQ 0 to DQ 7 data mask holding signal LDMH which is a signal of eight bits corresponding to respective ones of the above-mentioned 8-bit pre-fetched data, holds the data masking signal LDM, which has entered from the LDM terminal in synch with the serial pre-fetching of 8-bit data from the DQ terminals, until the end of the write command.
- the data mask holding signal LDMH is asserted to the high level when data is written to the memory cell array and is de-asserted to the low level at the end of the write operation.
- the potential precharged by the main transmission data line precharge circuit 302 will be described in detail later.
- the write amplifier 303 drives the main data transmission lines MIO_T, MIO_B based upon the logic level of the DQ 0 signal that has entered from the read/write bus RWBS and outputs the write data toward memory cell arrays 301 n (where only A and B are shown as n in FIG. 3 ).
- the main amplifier 304 When a read command is executed, the main amplifier 304 amplifies read data that has been sent from the memory cell arrays 301 n through the local data transmission lines (local data line pair: local I/O lines) LIOnT, LIOnB (where only A and B are shown as n in FIG. 3 ) and main data transmission lines MIO_T, MIO_B, converts this data to serial data and outputs the serial data to the read/write bus RWBS.
- local data transmission lines local data line pair: local I/O lines
- LIOnT local I/O lines
- LIOnB where only A and B are shown as n in FIG. 3
- main data transmission lines MIO_T, MIO_B converts this data to serial data and outputs the serial data to the read/write bus RWBS.
- the memory cell array A 301 A and memory cell array B 301 B are memory cell arrays in which DRAM cells have been disposed in matrix form in correspondence with the intersections between bit lines BLAnT, BLAnB, BLBnT, BLBnB and word lines (not shown). Since the internal configuration of the DRAM memory cell array is well known, no further description is given here. Although only the two memory cell arrays 301 A and 301 B are shown in FIG. 3 , a larger number may be provided.
- n mat selection signal (n is A and B in FIG. 3 ) is connected to each word driver.
- An n mat selection signal is a signal which, when a row address is designated by an ACT command, is activated based upon the designated address.
- the word driver 311 activates the designated word line based upon the designated row address.
- Bit lines BLA 0 T, BLA 0 B, etc., of the memory cell arrays 301 A, 301 B are arranged as a bit-line pair for transmitting a pair of complementary signals comprising a non-inverted signal BLA 0 T, etc., and an inverted signal BLA 0 B, etc.
- the sense amplifiers 310 are connected to the respective bit-line pairs BLA 0 T, BLA 0 B, etc.
- the sense amplifiers 310 are used to amplify data that has been read out of the memory cells corresponding to the designated word lines. They are used for write-back when the DRAM cells are refreshed and when data from memory cells is read out externally in conformity with a read command.
- Selection switches (Y switches: YSWAn, YSWBn) 307 are switches connecting bit lines BLA 0 T, BLA 0 B, etc., and local data transmission lines LIOnT, LIOnB (n is A and B in FIG. 3 ).
- the selection switches 307 are provided in correspondence with the bit-line pairs BLA 0 T, BLA 0 B, etc., of the memory cell arrays, and respective ones of selection switch selection signals YSn are connected to them.
- the selection switch selection signals YSn are asserted to the high level when selected by column addresses and connect selected bit-line pairs and the local data transmission line pairs LIOnT, LIOnB.
- the local data transmission lines (local data line pair: local I/O lines) LIOnT, LIOnB (n is A and B in FIG. 3 ) are data transmission lines provided in correspondence with each memory cell array 301 n .
- the local data transmission lines are connected to the main data transmission lines MIO_T, MIO_B via local data line selection switches 305 .
- the main data transmission lines MIO_T, MIO_B connected via the local data line selection switches 305 to the local data transmission lines LIOnT, LIOnB provided in correspondence with each of the memory cell arrays 301 n function overall as data transmission lines that transmit data between the write amplifier 303 and main amplifier 304 and each of the memory cell arrays 310 n .
- the local data transmission lines LIOnT, LIOnB are also data transmission lines that transmit a pair of complementary signals comprising non-inverted signal LIOnT and the inverted signal LIOnB in a manner similar to that of the main data transmission lines MIO_T, MIO_B. Further, these are bi-directional data transmission lines for transmitting data, which has been read out of the memory cell arrays 301 n , to the main data transmission lines MIO_T, MIO_B and for transmitting write data, which has been transmitted from the write amplifier 303 through the main data transmission lines MIO_T, MIO_B, to the memory cell arrays 301 n.
- the local data line selection switches (LIOSW) 305 are provided in correspondence with the local data transmission lines LIOnT, LIOnB and connect the corresponding local data transmission lines LIOnT, LIOnB with the main data transmission lines MIO_T, MIO_B. Connected to the local data line selection switches 305 are local data line selection switch control signals LIOSWn (n is A and B in FIG. 3 ). When the local data line selection switch control signal LIOSWn has been asserted to the high level, the corresponding local data transmission lines LIOnT, LIOnB and the main data transmission lines MIO_T, MIO_B are connected.
- a local data transmission line precharge circuit 309 is provided for the local data transmission lines LIOnT, LIOnB.
- the n mat selection signal (n is A and B in FIG. 3 ) and the precharge signal PCH-B are connected to each local data transmission line precharge circuit 309 .
- the n mat selection signal connected to the local data transmission line precharge circuit 309 is asserted to the high level in response to receipt of an ACT command, the precharge potential of this local data transmission line pair LIOnT, LIOnB rises to the supply voltage (VPERI) of the peripheral circuit.
- FIG. 5 is a circuit diagram showing the circuit arrangement within blocks of circuitry relating to the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB from the write amplifier 303 to the bit lines BLA 0 T, BLA 0 B of the memory cell array A 301 A.
- the circuit arrangement of FIG. 5 will now be described.
- the write amplifier 303 and data transmission line precharge circuits 302 A, 302 B are supplied with power from VPERI, which is the power supply of the peripheral circuit.
- the memory cell array and the sense amplifier 310 are supplied with power from VARY, the voltage of which is lower than that of VPERI of the peripheral circuit.
- a P-channel MOS transistor is represented by MP_XX
- an N-channel MOS transistor is represented by MN_XX.
- the data transmission line precharge circuit in FIG. 5 includes the data transmission line precharge circuit 302 A, which precharges the main data transmission line pair MIO_T, MIO_B to the VPERI potential when the precharge signal PCH-B is asserted to the low level by execution of the precharge command, and the data transmission line precharge circuit 302 B, which changes the precharge potential to a potential lower than the VPERI potential in response to receipt of the write command for performing data masking.
- the write amplifier 303 sets one of the main data transmission lines MIO_T, MIO_B to the VPERI potential (high level) and the other to the VSS potential (low level) in accordance with the logic level of the DQ 0 signal.
- the local data line selection switch 305 and selection switch 307 are both constituted by N-channel MOS transistors.
- the data transmission lines MIO_T, MIO_B, LIOAT, LIOAB be precharged to the high potential (VPERI potential).
- the sense amplifier 310 When power is applied to PCS and NCS, the sense amplifier 310 is activated and amplifies the potential difference of the bit-line pair BLA 0 T, BLA 0 B. Owing to the precharge circuit of the bit lines (not shown), the bit-line pair BLA 0 T, BLA 0 B is precharged to the intermediate potential (1 ⁇ 2 VARY potential) of the same potentials by execution of the precharge command.
- the precharge circuit ( 309 in FIG. 3 ) of the local data transmission lines LIOAT, LIOAB is not shown in FIG. 5 , the function thereof is as already described above in conjunction with FIG. 3 .
- FIG. 4 is an operation waveform diagram in the case of the write mode in which data masking is performed in the semiconductor memory 100 .
- the operation of the semiconductor memory 100 will be described with reference to FIG. 4 .
- the precharge signal PCH-B is asserted to the low level and the local data transmission lines LIOAT, LIOAB are precharged to the intermediate potential (1 ⁇ 2 VARY potential).
- the main data transmission lines MIO_T, MIO_B are precharged to the high potential (VPERI potential).
- the n mat selection signal is de-asserted to the low level by execution of the precharge command PRE.
- the local data line selection switch control signal LIOSWA also is de-asserted to the low level, the local data line selection switch 305 is turned OFF and the main data transmission lines MIO_T, MIO_B are disconnected from the local data transmission lines LIOAT, LIOAB. Further, selection switch selection signal YS 0 also is de-asserted to the low level and all of the selection switches 307 are turned OFF.
- the bit-line pair BLA 0 T, BLA 0 B is precharged to the intermediate potential (1 ⁇ 2 VARY potential) by execution of the precharge command PRE.
- the reason for precharging the local data transmission lines LIOAT, LIOAB to the intermediate potential (1 ⁇ 2 VARY potential) is to so arrange it that a feed-through current will not flow between the bit-line pair BLA 0 T, BLA 0 B and the local data transmission lines LIOAT, LIOAB via the selection switches 307 owing to precharging to a potential identical with the precharge potential (1 ⁇ 2 VARY potential) of the bit lines.
- the A mat selection signal is asserted to the high level by designation of the row address.
- the word line of the selected memory cell array A 301 A is activated in accordance with the designation of the row address and the data in the memory cell is read from the memory cell of the memory cell array A 301 A to the sense amplifier via the bit lines BLA 0 T, BLA 0 B.
- the sense amplifier 310 is activated and the potential difference between the bit lines BLA 0 T, BLA 0 B is amplified. It should be noted that the memory cell array B for which there is no row-address designation is held in the precharged state.
- the potential of the bit-line pair also remains at the intermediate potential (1 ⁇ 2 VARY potential) of the same potentials.
- the precharge potential of the local data transmission lines LIOAT, LIOAB of the A mat is changed to the high potential (VPERI potential).
- the precharge potential of the local data transmission lines LIOBT, LIOBB of the B mat remains the intermediate potential (1 ⁇ 2 VARY potential).
- the reason for raising the precharge potential of the local data transmission lines LIOAT, LIOAB of the A mat, selected by execution of the ACT command, to VPERI is that the core of the arrangement is NMOS, according to which the main amplifier 304 that receives the read data and the sense amplifier 310 that receives the write data both exhibit little process variations and have a small area. Further, since the selection switch 307 and local data line selection switch 305 are constituted by N-channel MOS transistors, the high level is not readily transmitted.
- the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB be a high level, or more specifically, VPERI, which is the supply voltage level of the peripheral circuit.
- the precharge potential of the local data transmission lines LIOBT, LIOBB of mat B which has not been selected, holds the intermediate potential (1 ⁇ 2 VARY potential). This is to prevent the flow of a feed-through current between the bit-line pair BLA 0 T, BLA 0 B and the local data transmission lines LIOAT, LIOAB via the selection switch 307 when the selection switch selection signal YSn is asserted and attains the high level.
- the precharge signal PCH-B is de-asserted and attains the high level. Accordingly, precharging of the main data transmission lines MIO_T, MIO_B to the VPERI potential is removed. Further, the DQ 0 to DQ 7 data mask holding signal LDMH is asserted to the high level. Furthermore, the write-amplifier enable signal WAE is asserted to the high level and the data mask precharge signal LDMPRE is asserted to the high level for a fixed period of time. When this occurs, the N-channel MOS transistors MN_D 0 and MN_D 1 of the data transmission line precharge circuit of FIG.
- the LDMPRE signal is de-asserted to the low level at least by the time the selection switch selection signal YSO is asserted to the high level.
- the local data transmission line selection switch control signal LIOSWA is asserted to the high level and the local data line selection switch 305 connecting the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB conducts. Accordingly, with the drop in the potential of the main data transmission lines MIO_T, MIO_B, the potential of the local data transmission lines LIOAT, LIOAB also drops.
- the selection switch selection signal YS 0 is asserted to the high level.
- the corresponding selection switch 307 (YSWA 0 in FIG. 3 ) conducts and the voltage of the bit lines BLA 0 T, BLA 0 B amplified by the sense amplifier 310 is output to the local data transmission lines LIOAT, LIOAB.
- the local data line selection switch 305 since the local data line selection switch 305 is conducting, a change in the potential of the local data transmission lines LIOAT, LIOAB is accompanied by a change also in the potential of the main data transmission lines MIO_T, MIO_B.
- the selection switch 307 when the selection switch 307 conducts, the precharging operation is completed and therefore the precharge transistors connected to the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB are not conducting.
- the potential of the bit lines BLA 0 T, BLA 0 B is influenced by the potential of the electric charge being held in the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB.
- the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB remains at VPERI.
- the potential VPERI of the power supply level of the peripheral circuit is a potential higher than the high-level potential VARY (the supply voltage level of the cell array) at which the sense amplifier 310 holds data. Accordingly, in a case where the transistors that construct the sense amplifier 310 are unbalanced, there is the danger that the data held by the sense amplifier 310 will be inverted by the potential of the data transmission lines.
- the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB is lowered by the data mask precharge signal LDMPRE. This means that the logic level of the sense amplifier will not be inverted even if the potential of the bit lines BLA 0 T, BLA 0 B is influenced somewhat by conduction of the selection switch 307 .
- the data mask holding signal LDMH also is de-asserted to the low level and so is the write-amplifier enable signal WAE.
- the precharge command PRE is executed again, the precharge signal PCH-B is asserted to the low level and the A mat selection signal is de-asserted to the low level.
- the local data line selection signal LIOSWA is de-asserted to the low level and the local data line selection switch is turned OFF, thereby disconnecting the main data transmission lines MIO_T, MIO_B and the local data transmission lines LIOAT, LIOAB.
- the selection switch selection signal YS 0 also is de-asserted to the low level, the main data transmission lines MIO_T, MIO_B are precharged to the VPERI potential and the local data transmission lines LIOAT, LIOAB and bit lines BLA 0 T, BLA 0 B are precharged to 1 ⁇ 2 VARY to restore the initial state.
- the selection switch 307 conducts first and then the local data line selection switch 305 conducts thereafter. Accordingly, data masking is carried out and, as at the time of execution of the write command, the electric charge on the main data transmission lines MIO_T, MIO_B and local data transmission lines does not flow into the bit lines BLA 0 T, BLA 0 B at one stroke owing to conduction of the selection switch 307 .
- the precharge potential of the data transmission lines is a potential for which VPERI is suitable.
- FIG. 7 is an operation waveform diagram at the time of execution of the write command in a case where bits that are data-masked and bits that are not data-masked are mixed with regard to serially prefetched data of four bits.
- LDM terminal and similarly also for the UDM terminal and DM terminal
- FIG. 7 out of four bits of serially input data, two bits MIO 0 , MIO 2 undergo data masking and two bits MIO 1 , MIO 3 are written without undergoing data masking.
- the main data transmission lines MIO are all precharged to the VPERI potential before execution of the write command WRITE.
- the precharge potential VPERI is lowered by activation of the LDMPRE signal.
- the output buffer of the write amplifier 303 conducts and data that has entered from the DQ terminals is output as complementary signals to the main data transmission lines MIO and is driven to VPERI and VSS.
- the selection switch 307 opens and the main data transmission line MIO and bit line BL are connected via the local data transmission line LIO.
- the potential of the bit line BL is output also to the main data transmission line MIO.
- the data of the sense amplifier 310 is rewritten by the output data of the write amplifier 303 and the output data of the write amplifier 303 remains as the potential of the main data transmission line MIO.
- the potential of the main data transmission line MIO is precharged to the potential of the power supply level VPERI of the peripheral circuitry irrespective of whether data masking has been performed by execution of the precharge command PRE.
- FIG. 6A is an exemplary embodiment in which the precharge circuit at the time of the write mode for performing data masking is used also as a discharging N-channel MOS transistor of a write amplifier 603 .
- the area of the precharge circuit can be reduced because it is not necessary to newly provide an N-channel MOS transistor for precharge level adjustment at the time of the write mode in which data masking is performed.
- blocks circuits enclosed by the dashed-line rectangles that are no different from those of the circuit of FIG. 5 are designated by the same reference characters as those used in FIG. 5 and are not described again.
- FIG. 6B is a data transmission line precharge circuit 302 C in which the power supply of the source of the N-channel MOS transistor in the precharge circuit 302 B at the time of the write operation in which data masking is performed in FIG. 5 is changed from VSS to the power supply VARY of the memory cell array.
- This circuit is identical with the circuit of FIG. 5 in other respects. Since the potential of VARY is close to the potential of VPERI, the potential level of the main data transmission lines MIO_T, MIO_B can be changed more gently than when VSS is used.
- FIG. 8 is an example of data transmission line precharge circuits 302 D, 302 E in a case where the precharge potential of the main data transmission lines MIO_T, MIO_B is made VSS and not VPERI.
- the precharge potential is raised by the data transmission line precharge circuit 302 E.
- a main amplifier 304 A also is changed in a case where a change is necessary owing to a change in precharge potential.
- the selection switch 307 and local data line selection switch 305 remain constituted by N-channel MOS transistors.
- the selection switch and local data line selection switch may just as well be constituted by P-channel MOS transistors.
- a data transmission line precharge circuit corresponding to the second write mode for performing data masking is mainly provided for the main data transmission lines MIO_T, MIO_B.
- the data transmission line precharge circuit may also be provided for the local data transmission lines LIOn_T, LIOn_B.
- a data transmission line precharge circuit corresponding to the write mode for performing data masking preferably is provided for the main data transmission lines MIO_T, MIO_B.
- the present invention is not limited to a DRAM.
- the invention is applicable generally to a semiconductor memory having a write mode in which data masking is performed and a write mode in which data masking is not performed.
- the invention is not limited to a semiconductor memory.
- precharging to a potential ideal for data write can be performed when data masking is not carried out, and the precharge potential can be made a potential of little influence on the side that receives data.
- operation on the side that receives data need not be changed depending upon whether or not data masking is performed.
- precharged can be performed to the high level or low level.
- precharged can be performed to a potential that is intermediate the high and low levels.
- the invention is applicable to a precharge circuit of data transmission lines to a write mode in which data is written to the SRAM cell or register without performing data masking and a write mode in which data masking is performed.
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Abstract
Description
- This application is based upon and claims the benefit of the priority of Japanese patent application No. 2009-193327, filed on Aug. 24, 2009, the disclosure of which is incorporated herein in its entirety by reference thereto.
- This invention relates to a semiconductor memory and semiconductor device. More particularly, the invention relates to a semiconductor memory and semiconductor device having a write mode in which data masking is performed and a write mode in which data masking is not performed.
- In the field of semiconductor devices such as semiconductor memories, advances in process microfabrication in recent years have made possible the practical utilization of semiconductor devices of greater scale, and advances are also being made in lowering the voltage of the power supply for such semiconductor devices. Progress in lowering the voltage of the semiconductor device power supply has been accompanied by use of lower voltages for memory cell arrays in DRAMs, for example, and it is important to reduce voltage fluctuations in the power source and signals in the vicinity of sense amplifiers.
- A semiconductor device such as a memory known in the art has a function for masking data when data is written. For example,
Patent Document 1 describes a semiconductor storage device in which write data is input to a synchronous DRAM at a speed that is an integral number of times greater than the clock frequency, a data masking signal is input in synch with the input data and data masking can be performed for every bit of the write data. - Japanese Patent Kokai Publication No. JP-H11-45568A, which corresponds to U.S. Pat. No. 6,052,330.
- The entire disclosures of the above-mentioned Patent Documents are incorporated herein by reference thereto.
- The analysis below is given by the present invention. Problems relating to data masking will be described taking a DRAM as an example. In the ordinary write mode in which masking of data is not performed, data received externally is sent through a write amplifier and data transmission line and is written to a memory cell via a sense amplifier selected by a column address.
- On the other hand, in a write mode in which data is masked, the write amplifier does not operate to send the data to the data transmission line. The data transmission line is connected, while still in the pre-charged state, to the sense amplifier selected by the column address. The potential on the bit line of the sense amplifier fluctuates owing to charge sharing when the selection switch that connects the data transmission line and the sense amplifier is turned on by the column address.
- Ordinarily, the data in the sense amplifier will not be destroyed even if fluctuation of the bit-line potential occurs. However, it is conceivable that the sense amplifier will perform signal inversion erroneously if an imbalance in the threshold value becomes too large owing to process variations. In particular, since microfabrication is accompanied by a decline in the supply voltage of the memory cell array, measures for dealing with the write mode in which data masking is performed have become important.
- According to a first aspect of the present invention, there is provided a semiconductor memory including a data transmission line and a data transmission line precharge circuit. The data transmission line precharge circuit sets a precharge potential of a data transmission line to a first potential at the time of a first write mode in which data masking is not performed. And the data transmission line precharge circuit sets the precharge potential to a potential different from the first potential at the time of a second write mode in which data masking is performed.
- According to a second aspect of the present invention, there is provided a semiconductor memory including a memory cell array including a plurality of bit lines, a plurality of selection switches each connected to a corresponding one of the plurality of bit lines, a plurality of write amplifiers, and a plurality of data transmission line pairs. Each of the transmission line pairs which connects a corresponding one of the write amplifiers and corresponding ones of the plurality of selection switches. Each of the plurality of data transmission line pairs transmits output data of the corresponding write amplifier as a pair of complementary signals, which includes a non-inverted signal and an inverted signal, at write time. The semiconductor memory further includes a data transmission line precharge circuit precharges the plurality of data transmission line pairs to a first potential and subsequently sets, to an intermediate potential, a precharge potential of a data transmission line pair that performs data masking among the plurality of data transmission line pairs at write time. The intermediate potential is a potential that is intermediate the first potential and a second potential at which the write amplifier discharges one data transmission line of a data transmission line pair that does not perform data masking at write time.
- According to a third aspect of the present invention, there is provided a semiconductor device including write amplifiers of a plurality of bits, data transmission lines of a plurality of bits connected to respective ones of the write amplifiers of the plurality of bits, and a plurality of flip-flops connected to the data transmission lines of each of the bits via respective ones of selection switches. The semiconductor device further including a data transmission line precharge circuit that exercises control such that before data of the plurality of bits is written from the write amplifiers to flip-flops selected by the selection switches via the data transmission lines, precharge potential of the data transmission lines is made a first potential with regard to bits that do not perform data masking, and precharge potential of data transmission lines that perform data masking is made a potential different from the first potential.
- The meritorious effects of the present invention are summarized as follows.
- In accordance with the present invention, data write is executed after a data transmission line is precharged to a potential when data masking is performed and to a different potential when data masking is not performed. When data masking is not performed, therefore, precharging is performed to a potential at which data can be written in excellent fashion. When data masking is carried out, precharging can be performed to a potential that suppresses a fluctuation in bit-line potential.
- Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
-
FIG. 1 is a block diagram illustrating the entirety of a semiconductor memory according to an exemplary embodiment of the present invention; -
FIG. 2 is a block diagram illustrating abank 0 of semiconductor memory according to the exemplary embodiment; -
FIG. 3 is a block diagram illustrating DQ0 ofbank 0 in the semiconductor memory according to the exemplary embodiment; -
FIG. 4 is an operation waveform diagram in the case of a write mode in which data masking is performed in the semiconductor memory according to the exemplary embodiment; -
FIG. 5 is a circuit diagram of a read/write control circuit in the semiconductor memory according to the exemplary embodiment; -
FIG. 6A is a circuit diagram illustrating a modification andFIG. 6B a circuit diagram illustrating another modification of a data transmission line precharge circuit and write amplifier circuit in the semiconductor memory according to the exemplary embodiment; -
FIG. 7 is an operation waveform diagram in the case of a write mode of bits in which data masking is performed and of bits in which data masking is not performed in the semiconductor memory according to an exemplary embodiment; and -
FIG. 8 is a circuit diagram illustrating another modification of a data transmission line precharge circuit in the semiconductor memory according to the exemplary embodiment. - The present invention provides a semiconductor memory having a data transmission line precharge circuit for exercising control such that a precharge potential of a data transmission line is made a first potential at the time of a first write mode in which data masking is not performed, and the precharge potential of the data transmission line is made a potential different from the first potential at the time of a second write mode in which data masking is performed. When data masking is not performed, therefore, precharging can be performed to a potential suited to high-speed data write. When data masking is carried out, precharging can be performed to a potential that suppresses a fluctuation in the potential of a bit line connected to the data transmission line.
- In accordance with the arrangement described above, the side of a memory cell array that receives data on a data transmission line need not have its circuit configuration or operation changed depending upon whether or not data masking is carried out. Further, in a case where data of a plurality of bits is written in parallel, whether data masking is to be performed can easily be set on a bit-by-bit basis.
- Preferred exemplary embodiments of the present invention will now be described in detail with reference to the drawings.
-
FIG. 1 is a block diagram illustrating the entirety of a semiconductor memory according to this exemplary embodiment of the present invention. As shown inFIG. 1 , asemiconductor memory 100 is a DDR3 SDRAM (Double-Data-Rate 3 Synchronous Dynamic Random-Access Memory) includes eight banks. It should be noted that this DDR3 SDRAM is strictly an example of a preferred exemplary embodiment and the scope of application of the present invention is not limited to a DDR3 SDRAM. The invention is applicable to a semiconductor memory other than a DRAM and to a semiconductor device other than a semiconductor memory. - The
semiconductor memory 100 is provided with 16 data input/output terminals 103 corresponding to bits DQ0 to DQ15. Each data input/output terminal 103 is connected to a read/write control circuit 102 of each bank via an input/output circuit, not shown. Memorycell array areas 101 ofbanks 0 to 7 are arranged by being divided into eight lower-order bits (DQ0 to DQ7) and eight higher-order bits (DQ8 to DQ15) (namely into left and right halves as shown in the drawing). The read/write control circuit 102 is provided for every memorycell array area 101 of each bank of the eight lower-order bits and eight higher-order bits. Among the 16 data input/output terminals (DQ0 to DQ15), the data input/output terminals (DQ0 to DQ7) of the eight lower-order bits are connected to the read/write control circuit 102 corresponding to the memory cell array area in which the eight lower-order bits are disposed, and the data input/output terminals (DQ8 to DQ15) of the eight higher-order bits are connected to the read/write control circuit 102 corresponding to the memory cell array area in which the eight higher-order bits are disposed. - An
LDM terminal 105 and aUDM terminal 106 are terminals for data-masking write data of the eight lower-order bits (DQ0 to DQ7) and eight higher-order bits (DQ8 to DQ15), respectively. Whether masking is performed or not can be changed over for every bit of data, which is input serially from the corresponding data input/output terminals (DQ0 to DQ7, DQ8 to DQ15), using both edges, namely the rising and falling edges of a data strobe signal (DQS) (not shown), as a reference. - The LDM terminal is connected to the read/
write control circuits 102 corresponding to the memory cell array areas 101 (the memorycell array areas 101 on the left side inFIG. 1 ) in which the bits DQ0 to DQ7 of each bank are disposed. Similarly, the UDM terminal is connected to the read/write control circuits 102 corresponding to the memory cell array areas 101 (the memorycell array areas 101 on the right side inFIG. 1 ) in which the bits DQ8 to DQ15 of each bank are disposed. -
FIG. 2 is a blockdiagram illustrating bank 0 of semiconductor memory.FIG. 2 corresponds to a diagram obtained by extracting the memorycell array areas 101 and read/write control circuits 102 ofbank 0 of lower-order bits (DQ0 to DQ7) andbank 0 of higher-order bits (DQ8 to DQ15). A read/write bus RWBS, which includes bus wiring connected to the data input/output terminals (DQ0 to DQ7), and an LDM signal, which is a DQ0 to DQ7 data masking signal connected to theLDM terminal 105, are connected to the read/write control circuit 102 of the lower-order bits (DQ0 to DQ7). Similarly, a read/write bus RWBS connected to the data input/output terminals (DQ8 to DQ15), and a UDM signal, which is a DQ8 to DQ15 data masking signal, are connected to the read/write control circuit 102 of the higher-order bits (DQ8 to DQ15). - The read/
write control circuits 102 are connected to the memorycell array areas 101 of the bits (DQ0 to DQ7, DQ8 to DQ15) via main data transmission lines (main I/O lines) MIO_T, MIO_B. The main data transmission lines MIO_T, MIO_B are bi-directional data transmission lines and are used in data transmission for writing write data and reading read data. These data transmission lines are data transmission lines for transmitting complementary signals comprising a non-inverted signal (True) and an inverted signal (Bar, namely the complement of the True signal). - The memory
cell array area 101 has been divided into individual bits (DQ0 to DQ15). Disposed in the memorycell array area 101 of every bit, in addition to the memory cell array per se, are local data transmission lines (local I/O lines) LIO_T, LIO_B, selection switches (Y switches) and sense amplifiers, etc. The local data transmission lines LIO_T, LIO_B are data transmission lines connecting the main data transmission lines MIO_T, MIO_B and the memory cell array. The selection circuits are switches connecting the local data transmission lines LIO_T, LIO_B and the bit lines of the memory cell array. The sense amplifiers are connected to the bit lines of the memory cell array and amplify the bit-line potentials read out of the memory cells. - The read/
write control circuit 102 is a circuit for controlling the read/write operation of the memory cell array. At the time of the write operation, write data that has been sent in serially via the read/write bus RWBS is converted to parallel data by the read/write control circuit 102 and is written to the memory cell array. For example, in the case of a DDR3 SDRAM, 8-bit pre-fetch is employed and therefore the write data that has been sent in serially from the read/write bus RWBS is rearranged into 8-bit parallel data and sent to the memory cell array in 8-bit parallel fashion via the data transmission lines. Specifically, for the single bit DQ0, there are eight sets of the main data transmission lines MIO_T, MIO_B, and data is written to the memory cell array in 8-bit parallel fashion (in the case where there is no data masking). Similarly, for each of bits DQ1 to DQ15, there are eight sets of the main I/O lines MIO_T, MIO_B. Therefore, for the total of 16 bits DQ0 to DQ15, 8 sets×16 DQ bits=128 sets of the main data transmission lines exist. -
FIG. 3 is a block diagram illustrating a portion of DQ0 ofbank 0 in thesemiconductor memory 100. As mentioned above, there are eight sets MIO0 to MIO7 of the main data transmission lines MIO_T, MIO_B in DQ0 ofbank 0. InFIG. 3 , however, only one set of the main data transmission lines MIO_T, MIO_B is shown. Further,FIG. 3 includes the read/write control circuit 102 and the circuit of the memorycell array area 101 of the portion relating to DQ0 ofbank 0 inFIG. 2 . InFIG. 3 , a main data line precharge circuit (data transmission line precharge circuit) 302, awrite amplifier 303 and amain amplifier 304 correspond to the read/write control circuit 102 inFIG. 2 , and the other blocks correspond to the memorycell array area 101. - In
FIG. 3 , the main data line precharge circuit (data transmission line precharge circuit) 302 precharges the main data transmission lines MIO_T, MIO_B. The main data transmission lines MIO_T, MIO_B transmit a pair of complementary signals comprising a non-inverted signal and an inverted signal. A precharge signal (inverted signal) PCH-B is connected to the main data lineprecharge circuit 302 as a signal for controlling precharging. A write-amplifier enable signal WAE, a DQ0 to DQ7 data mask holding signal LDMH and a data mask precharge signal LDMPRE are connected to the main data lineprecharge circuit 302 as signals for controlling precharge potential at the time of a second write mode, which is a mode for performing data masking. The DQ0 to DQ7 data mask holding signal LDMH, which is a signal of eight bits corresponding to respective ones of the above-mentioned 8-bit pre-fetched data, holds the data masking signal LDM, which has entered from the LDM terminal in synch with the serial pre-fetching of 8-bit data from the DQ terminals, until the end of the write command. In the case where data masking is performed, the data mask holding signal LDMH is asserted to the high level when data is written to the memory cell array and is de-asserted to the low level at the end of the write operation. The potential precharged by the main transmission data lineprecharge circuit 302 will be described in detail later. - When the write command has been received and the write-amplifier enable signal WAE asserted to the high level, the
write amplifier 303 drives the main data transmission lines MIO_T, MIO_B based upon the logic level of the DQ0 signal that has entered from the read/write bus RWBS and outputs the write data toward memory cell arrays 301 n (where only A and B are shown as n inFIG. 3 ). - When a read command is executed, the
main amplifier 304 amplifies read data that has been sent from the memory cell arrays 301 n through the local data transmission lines (local data line pair: local I/O lines) LIOnT, LIOnB (where only A and B are shown as n inFIG. 3 ) and main data transmission lines MIO_T, MIO_B, converts this data to serial data and outputs the serial data to the read/write bus RWBS. - The memory
cell array A 301A and memorycell array B 301B are memory cell arrays in which DRAM cells have been disposed in matrix form in correspondence with the intersections between bit lines BLAnT, BLAnB, BLBnT, BLBnB and word lines (not shown). Since the internal configuration of the DRAM memory cell array is well known, no further description is given here. Although only the twomemory cell arrays FIG. 3 , a larger number may be provided. - Provided in correspondence with the
memory cell arrays word drivers 311 for driving designated word lines of designated memory cell arrays based upon the respective row addresses. An n mat selection signal (n is A and B inFIG. 3 ) is connected to each word driver. An n mat selection signal is a signal which, when a row address is designated by an ACT command, is activated based upon the designated address. When the memorycell array A 301A or memorycell array B 301B has been selected inFIG. 3 , the corresponding A mat selection signal or B mat selection signal is activated. When the n mat selection signal is activated, theword driver 311 activates the designated word line based upon the designated row address. - Bit lines BLA0T, BLA0B, etc., of the
memory cell arrays sense amplifiers 310 are connected to the respective bit-line pairs BLA0T, BLA0B, etc. Thesense amplifiers 310 are used to amplify data that has been read out of the memory cells corresponding to the designated word lines. They are used for write-back when the DRAM cells are refreshed and when data from memory cells is read out externally in conformity with a read command. - Selection switches (Y switches: YSWAn, YSWBn) 307 are switches connecting bit lines BLA0T, BLA0B, etc., and local data transmission lines LIOnT, LIOnB (n is A and B in
FIG. 3 ). The selection switches 307 are provided in correspondence with the bit-line pairs BLA0T, BLA0B, etc., of the memory cell arrays, and respective ones of selection switch selection signals YSn are connected to them. The selection switch selection signals YSn are asserted to the high level when selected by column addresses and connect selected bit-line pairs and the local data transmission line pairs LIOnT, LIOnB. - The local data transmission lines (local data line pair: local I/O lines) LIOnT, LIOnB (n is A and B in
FIG. 3 ) are data transmission lines provided in correspondence with each memory cell array 301 n. The local data transmission lines are connected to the main data transmission lines MIO_T, MIO_B via local data line selection switches 305. The main data transmission lines MIO_T, MIO_B connected via the local data line selection switches 305 to the local data transmission lines LIOnT, LIOnB provided in correspondence with each of the memory cell arrays 301 n function overall as data transmission lines that transmit data between thewrite amplifier 303 andmain amplifier 304 and each of the memory cell arrays 310 n. The local data transmission lines LIOnT, LIOnB are also data transmission lines that transmit a pair of complementary signals comprising non-inverted signal LIOnT and the inverted signal LIOnB in a manner similar to that of the main data transmission lines MIO_T, MIO_B. Further, these are bi-directional data transmission lines for transmitting data, which has been read out of the memory cell arrays 301 n, to the main data transmission lines MIO_T, MIO_B and for transmitting write data, which has been transmitted from thewrite amplifier 303 through the main data transmission lines MIO_T, MIO_B, to the memory cell arrays 301 n. - The local data line selection switches (LIOSW) 305 are provided in correspondence with the local data transmission lines LIOnT, LIOnB and connect the corresponding local data transmission lines LIOnT, LIOnB with the main data transmission lines MIO_T, MIO_B. Connected to the local data line selection switches 305 are local data line selection switch control signals LIOSWn (n is A and B in
FIG. 3 ). When the local data line selection switch control signal LIOSWn has been asserted to the high level, the corresponding local data transmission lines LIOnT, LIOnB and the main data transmission lines MIO_T, MIO_B are connected. - A local data transmission line
precharge circuit 309 is provided for the local data transmission lines LIOnT, LIOnB. The n mat selection signal (n is A and B inFIG. 3 ) and the precharge signal PCH-B are connected to each local data transmission lineprecharge circuit 309. When the precharge command is executed, the precharge signal PCH-B is asserted to the low level and the local data transmission lines LIOnT, LIOnB are precharged to a voltage ½ VARY, which is intermediate the supply voltage (VARY) of the memory cell array 301 n and a clamp level VSS=0V. Further, when the n mat selection signal connected to the local data transmission lineprecharge circuit 309 is asserted to the high level in response to receipt of an ACT command, the precharge potential of this local data transmission line pair LIOnT, LIOnB rises to the supply voltage (VPERI) of the peripheral circuit. -
FIG. 5 is a circuit diagram showing the circuit arrangement within blocks of circuitry relating to the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB from thewrite amplifier 303 to the bit lines BLA0T, BLA0B of the memorycell array A 301A. The circuit arrangement ofFIG. 5 will now be described. - As shown in
FIG. 5 , thewrite amplifier 303 and data transmissionline precharge circuits sense amplifier 310 are supplied with power from VARY, the voltage of which is lower than that of VPERI of the peripheral circuit. InFIG. 5 , a P-channel MOS transistor is represented by MP_XX, and an N-channel MOS transistor is represented by MN_XX. - The data transmission line precharge circuit in
FIG. 5 includes the data transmission lineprecharge circuit 302A, which precharges the main data transmission line pair MIO_T, MIO_B to the VPERI potential when the precharge signal PCH-B is asserted to the low level by execution of the precharge command, and the data transmission lineprecharge circuit 302B, which changes the precharge potential to a potential lower than the VPERI potential in response to receipt of the write command for performing data masking. - When the corresponding data mask holding signal LDMH is de-asserted to the low level and the write-amplifier enable signal WAE is aserted to the high level, the
write amplifier 303 sets one of the main data transmission lines MIO_T, MIO_B to the VPERI potential (high level) and the other to the VSS potential (low level) in accordance with the logic level of the DQ0 signal. It should be noted that the local dataline selection switch 305 andselection switch 307 are both constituted by N-channel MOS transistors. Although the low level (VSS potential) driven by thewrite amplifier 303 can readily be transmitted up to the bit lines BLA0T, BLA0B, the high-level (VPERI) potential is not readily transmitted. The reason is that the potential difference across the gate and source becomes small when the transistor is turned ON. Accordingly, when data masking is not performed, it is preferred that the data transmission lines MIO_T, MIO_B, LIOAT, LIOAB be precharged to the high potential (VPERI potential). - When power is applied to PCS and NCS, the
sense amplifier 310 is activated and amplifies the potential difference of the bit-line pair BLA0T, BLA0B. Owing to the precharge circuit of the bit lines (not shown), the bit-line pair BLA0T, BLA0B is precharged to the intermediate potential (½ VARY potential) of the same potentials by execution of the precharge command. Although the precharge circuit (309 inFIG. 3 ) of the local data transmission lines LIOAT, LIOAB is not shown inFIG. 5 , the function thereof is as already described above in conjunction withFIG. 3 . -
FIG. 4 is an operation waveform diagram in the case of the write mode in which data masking is performed in thesemiconductor memory 100. The operation of thesemiconductor memory 100 will be described with reference toFIG. 4 . By executing a precharge command PRE, the precharge signal PCH-B is asserted to the low level and the local data transmission lines LIOAT, LIOAB are precharged to the intermediate potential (½ VARY potential). Further, the main data transmission lines MIO_T, MIO_B are precharged to the high potential (VPERI potential). Furthermore, the n mat selection signal is de-asserted to the low level by execution of the precharge command PRE. The local data line selection switch control signal LIOSWA also is de-asserted to the low level, the local dataline selection switch 305 is turned OFF and the main data transmission lines MIO_T, MIO_B are disconnected from the local data transmission lines LIOAT, LIOAB. Further, selection switch selection signal YS0 also is de-asserted to the low level and all of the selection switches 307 are turned OFF. The bit-line pair BLA0T, BLA0B is precharged to the intermediate potential (½ VARY potential) by execution of the precharge command PRE. - The reason for precharging the local data transmission lines LIOAT, LIOAB to the intermediate potential (½ VARY potential) is to so arrange it that a feed-through current will not flow between the bit-line pair BLA0T, BLA0B and the local data transmission lines LIOAT, LIOAB via the selection switches 307 owing to precharging to a potential identical with the precharge potential (½ VARY potential) of the bit lines.
- Next, when the ACT command is executed, the A mat selection signal is asserted to the high level by designation of the row address. When this occurs, the word line of the selected memory cell array A 301A is activated in accordance with the designation of the row address and the data in the memory cell is read from the memory cell of the memory cell array A 301A to the sense amplifier via the bit lines BLA0T, BLA0B. When the memory-cell data is read out to the sense amplifier, the
sense amplifier 310 is activated and the potential difference between the bit lines BLA0T, BLA0B is amplified. It should be noted that the memory cell array B for which there is no row-address designation is held in the precharged state. The potential of the bit-line pair also remains at the intermediate potential (½ VARY potential) of the same potentials. - Further, the precharge potential of the local data transmission lines LIOAT, LIOAB of the A mat is changed to the high potential (VPERI potential). The precharge potential of the local data transmission lines LIOBT, LIOBB of the B mat remains the intermediate potential (½ VARY potential). The reason for raising the precharge potential of the local data transmission lines LIOAT, LIOAB of the A mat, selected by execution of the ACT command, to VPERI is that the core of the arrangement is NMOS, according to which the
main amplifier 304 that receives the read data and thesense amplifier 310 that receives the write data both exhibit little process variations and have a small area. Further, since theselection switch 307 and local dataline selection switch 305 are constituted by N-channel MOS transistors, the high level is not readily transmitted. Accordingly, regardless of whether read or write is considered, it is preferred that, in a case where data is read and written, the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB be a high level, or more specifically, VPERI, which is the supply voltage level of the peripheral circuit. - On the other hand, the precharge potential of the local data transmission lines LIOBT, LIOBB of mat B, which has not been selected, holds the intermediate potential (½ VARY potential). This is to prevent the flow of a feed-through current between the bit-line pair BLA0T, BLA0B and the local data transmission lines LIOAT, LIOAB via the
selection switch 307 when the selection switch selection signal YSn is asserted and attains the high level. - Next, when a write command WRITE is executed, the precharge signal PCH-B is de-asserted and attains the high level. Accordingly, precharging of the main data transmission lines MIO_T, MIO_B to the VPERI potential is removed. Further, the DQ0 to DQ7 data mask holding signal LDMH is asserted to the high level. Furthermore, the write-amplifier enable signal WAE is asserted to the high level and the data mask precharge signal LDMPRE is asserted to the high level for a fixed period of time. When this occurs, the N-channel MOS transistors MN_D0 and MN_D1 of the data transmission line precharge circuit of
FIG. 5 conduct only during the time that the signal LDMPRE is at the high level, and the potential of the main data transmission lines MIO_T, MIO_B that have been charged to VPERI falls only by a fixed voltage. It should be noted that the potential drop of the voltage due to conduction of the N-channel MOS transistors MN_D0 and MN_D1 can be adjusted by the channel size of the N-channel MOS transistors MN_D0 and MN_D1 and time over which the LDMPRE signal is asserted to the high level. It should be noted that the LDMPRE signal is de-asserted to the low level at least by the time the selection switch selection signal YSO is asserted to the high level. - Owing to execution of the write command WRITE, the local data transmission line selection switch control signal LIOSWA is asserted to the high level and the local data
line selection switch 305 connecting the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB conducts. Accordingly, with the drop in the potential of the main data transmission lines MIO_T, MIO_B, the potential of the local data transmission lines LIOAT, LIOAB also drops. - Next, the selection switch selection signal YS0 is asserted to the high level. When this occurs, the corresponding selection switch 307 (YSWA0 in
FIG. 3 ) conducts and the voltage of the bit lines BLA0T, BLA0B amplified by thesense amplifier 310 is output to the local data transmission lines LIOAT, LIOAB. Further, since the local dataline selection switch 305 is conducting, a change in the potential of the local data transmission lines LIOAT, LIOAB is accompanied by a change also in the potential of the main data transmission lines MIO_T, MIO_B. - It should be noted that when the
selection switch 307 conducts, the precharging operation is completed and therefore the precharge transistors connected to the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB are not conducting. However, when theselection switch 307 conducts, the potential of the bit lines BLA0T, BLA0B is influenced by the potential of the electric charge being held in the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB. In particular, in the prior art, the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB remains at VPERI. The potential VPERI of the power supply level of the peripheral circuit is a potential higher than the high-level potential VARY (the supply voltage level of the cell array) at which thesense amplifier 310 holds data. Accordingly, in a case where the transistors that construct thesense amplifier 310 are unbalanced, there is the danger that the data held by thesense amplifier 310 will be inverted by the potential of the data transmission lines. - In this exemplary embodiment, on the other hand, the precharge potential of the main data transmission lines MIO_T, MIO_B and local data transmission lines LIOAT, LIOAB is lowered by the data mask precharge signal LDMPRE. This means that the logic level of the sense amplifier will not be inverted even if the potential of the bit lines BLA0T, BLA0B is influenced somewhat by conduction of the
selection switch 307. - Next, when the write operation ends, the data mask holding signal LDMH also is de-asserted to the low level and so is the write-amplifier enable signal WAE. When the precharge command PRE is executed again, the precharge signal PCH-B is asserted to the low level and the A mat selection signal is de-asserted to the low level. Furthermore, the local data line selection signal LIOSWA is de-asserted to the low level and the local data line selection switch is turned OFF, thereby disconnecting the main data transmission lines MIO_T, MIO_B and the local data transmission lines LIOAT, LIOAB. The selection switch selection signal YS0 also is de-asserted to the low level, the main data transmission lines MIO_T, MIO_B are precharged to the VPERI potential and the local data transmission lines LIOAT, LIOAB and bit lines BLA0T, BLA0B are precharged to ½ VARY to restore the initial state.
- Operation at execution of the read command will be described next. In a case where the read command is executed, the
selection switch 307 conducts first and then the local dataline selection switch 305 conducts thereafter. Accordingly, data masking is carried out and, as at the time of execution of the write command, the electric charge on the main data transmission lines MIO_T, MIO_B and local data transmission lines does not flow into the bit lines BLA0T, BLA0B at one stroke owing to conduction of theselection switch 307. When the sensing operation of themain amplifier 304 is considered, the precharge potential of the data transmission lines is a potential for which VPERI is suitable. -
FIG. 7 is an operation waveform diagram at the time of execution of the write command in a case where bits that are data-masked and bits that are not data-masked are mixed with regard to serially prefetched data of four bits. By changing the level of the LDM terminal (and similarly also for the UDM terminal and DM terminal) for every bit of the data input serially from the DQ terminal, it is possible to select, bit by bit, whether or not data masking is performed. InFIG. 7 , out of four bits of serially input data, two bits MIO0, MIO2 undergo data masking and two bits MIO1, MIO3 are written without undergoing data masking. As described above with reference toFIG. 3 , eight sets of the main data transmission lines MIO_T, MIO_B exist per DQ terminal (one bit), and data of four serially input bits is written in parallel using four sets of main data transmission lines of MIO0 to MIO3. During the period of execution of the write command, the data mask holding signal LDMH corresponding to MIO0, MIO2 is maintained at the high level. On the other hand, the data mask holding signal LDMH corresponding to MIO1, MIO3 remains at the low level. - As shown in
FIG. 7 , the main data transmission lines MIO are all precharged to the VPERI potential before execution of the write command WRITE. On the main data transmission lines of MIO0, MIO2 for performing data masking by start of execution of the write command WRITE, the precharge potential VPERI is lowered by activation of the LDMPRE signal. On the other hand, with regard to MIO1, MIO3 that do not perform data masking, the output buffer of thewrite amplifier 303 conducts and data that has entered from the DQ terminals is output as complementary signals to the main data transmission lines MIO and is driven to VPERI and VSS. When the selection switch selection signal YS attains the high level and is activated, theselection switch 307 opens and the main data transmission line MIO and bit line BL are connected via the local data transmission line LIO. On the MIO0, MIO2 that have undergone data masking, the potential of the bit line BL is output also to the main data transmission line MIO. With regard to the bits that do not undergo data masking, however, the data of thesense amplifier 310 is rewritten by the output data of thewrite amplifier 303 and the output data of thewrite amplifier 303 remains as the potential of the main data transmission line MIO. - Thereafter, the potential of the main data transmission line MIO is precharged to the potential of the power supply level VPERI of the peripheral circuitry irrespective of whether data masking has been performed by execution of the precharge command PRE.
- Described next are modifications of the data transmission line precharge circuit of the first exemplary embodiment, particularly the precharge circuit at the time of the write mode for performing data masking corresponding to 302B in
FIG. 5 .FIG. 6A is an exemplary embodiment in which the precharge circuit at the time of the write mode for performing data masking is used also as a discharging N-channel MOS transistor of awrite amplifier 603. The area of the precharge circuit can be reduced because it is not necessary to newly provide an N-channel MOS transistor for precharge level adjustment at the time of the write mode in which data masking is performed. It should be noted that blocks (circuits enclosed by the dashed-line rectangles) that are no different from those of the circuit ofFIG. 5 are designated by the same reference characters as those used inFIG. 5 and are not described again. -
FIG. 6B is a data transmission lineprecharge circuit 302C in which the power supply of the source of the N-channel MOS transistor in theprecharge circuit 302B at the time of the write operation in which data masking is performed inFIG. 5 is changed from VSS to the power supply VARY of the memory cell array. This circuit is identical with the circuit ofFIG. 5 in other respects. Since the potential of VARY is close to the potential of VPERI, the potential level of the main data transmission lines MIO_T, MIO_B can be changed more gently than when VSS is used. -
FIG. 8 is an example of data transmissionline precharge circuits line precharge circuit 302E. Further, amain amplifier 304A also is changed in a case where a change is necessary owing to a change in precharge potential. Furthermore, inFIG. 8 , theselection switch 307 and local dataline selection switch 305 remain constituted by N-channel MOS transistors. However, the selection switch and local data line selection switch may just as well be constituted by P-channel MOS transistors. - It should be noted that exemplary embodiments have been described in which a data transmission line precharge circuit corresponding to the second write mode for performing data masking is mainly provided for the main data transmission lines MIO_T, MIO_B. However, the data transmission line precharge circuit may also be provided for the local data transmission lines LIOn_T, LIOn_B. However, in order to reduce the number of elements of the data transmission line precharge circuit overall, a data transmission line precharge circuit corresponding to the write mode for performing data masking preferably is provided for the main data transmission lines MIO_T, MIO_B.
- Although exemplary embodiments relating to a DRAM have been described above, the present invention is not limited to a DRAM. For example, the invention is applicable generally to a semiconductor memory having a write mode in which data masking is performed and a write mode in which data masking is not performed. Furthermore, the invention is not limited to a semiconductor memory. In a semiconductor device having a function for writing data via a data transmission line and a function for performing data masking, precharging to a potential ideal for data write can be performed when data masking is not carried out, and the precharge potential can be made a potential of little influence on the side that receives data. In accordance with the present invention, operation on the side that receives data need not be changed depending upon whether or not data masking is performed. In particular, in the write mode in which data masking is not performed, precharged can be performed to the high level or low level. In the write mode in which data masking is performed, precharged can be performed to a potential that is intermediate the high and low levels.
- By way of example, if the
sense amplifier 310 inFIG. 5 is considered to be an SRAM cell or a flip-flop of a register, the invention is applicable to a precharge circuit of data transmission lines to a write mode in which data is written to the SRAM cell or register without performing data masking and a write mode in which data masking is performed. - It should be noted that other objects, features and aspects of the present invention will become apparent in the entire disclosure and that modifications may be done without departing the gist and scope of the present invention as disclosed herein and claimed as appended herewith. Also it should be noted that any combination of the disclosed and/or claimed elements, matters and/or items may fall under the modifications aforementioned.
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JP2009193327A JP2011044214A (en) | 2009-08-24 | 2009-08-24 | Semiconductor memory, and semiconductor device |
JP2009-193327 | 2009-08-24 |
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US20130163351A1 (en) * | 2011-12-21 | 2013-06-27 | Seung-Bong Kim | Data transmission circuit and semiconductor memory device having the same |
US20140211545A1 (en) * | 2013-01-31 | 2014-07-31 | Elpida Memory, Inc. | Semiconductor device |
US20140347945A1 (en) * | 2013-05-24 | 2014-11-27 | Micron Technology, Inc. | Apparatuses including a memory array with separate global read and write lines and/or sense amplifier region column select line and related methods |
US9390770B2 (en) | 2014-05-16 | 2016-07-12 | Micron Technology, Inc. | Apparatuses and methods for accessing memory including sense amplifier sections and coupled sources |
US9659611B1 (en) | 2015-12-09 | 2017-05-23 | SK Hynix Inc. | Semiconductor devices and semiconductor systems including the same |
WO2017172317A1 (en) * | 2016-03-28 | 2017-10-05 | Qualcomm Incorporated | Intelligent bit line precharge for reduced dynamic power consumption |
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CN112134337A (en) * | 2020-09-23 | 2020-12-25 | 维沃移动通信有限公司 | Power adapter, terminal device, electronic device and charging control method thereof |
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KR20150089539A (en) * | 2014-01-28 | 2015-08-05 | 에스케이하이닉스 주식회사 | Precharge circuit and semiconductor memory apparatus using the same |
KR102224954B1 (en) | 2014-05-16 | 2021-03-09 | 에스케이하이닉스 주식회사 | Semiconductor system and semiconductor device |
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WO2017172317A1 (en) * | 2016-03-28 | 2017-10-05 | Qualcomm Incorporated | Intelligent bit line precharge for reduced dynamic power consumption |
US10665558B2 (en) | 2017-12-11 | 2020-05-26 | Samsung Electronics Co., Ltd. | Semiconductor memory including pads arranged in parallel |
CN112134337A (en) * | 2020-09-23 | 2020-12-25 | 维沃移动通信有限公司 | Power adapter, terminal device, electronic device and charging control method thereof |
WO2022063067A1 (en) * | 2020-09-23 | 2022-03-31 | 维沃移动通信有限公司 | Power adapter, terminal device, electronic device, and charging control method thereof |
CN115798544A (en) * | 2023-02-13 | 2023-03-14 | 长鑫存储技术有限公司 | Read-write circuit, read-write method and memory |
WO2024168943A1 (en) * | 2023-02-13 | 2024-08-22 | 长鑫科技集团股份有限公司 | Read-write circuit, read-write method, and memory |
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